Method and apparatus for recovery of condensates



3 K. s. CLAPP METHOD AND APPARATUS FOR RECOVERY OF CONDENSATES Filed July 15, 1933 Smventor Patented Nov. 6, 1934 UNITED STATES PATENT. OFFICE METHOD AND APPARATUS FOR RECOVERY OF CONDENSATES sure relief mechanism or through the storage tank air vent.

In the traffic of gasoline, of the type used for motor fuel large reservoirs or tanks commonly known as bulk storage plants are customarily pro- 16 vided in the more thickly populated districts to accommodate the retail distribution of such fuel. These tanks are usually exposed to the weather and consequently must be equipped with air vents or safety valves" to permit the escapement of 20 vapors generated within the tank by variable thermal changes and agitation of the liquid. It has been the practice, in the past, to set such relief valves for operation at eight ounces to five pounds pressure and to permit the vapors to es- 26 cape to atmosphere. Although some effort has been made to restrict the egress of such gases through the relief valves and to confine the condensates within the tank, it has been found that the loss by evaporation or release to atmosphere 30 of the vapor varies from one-half to six per cent by volume; moreover, that the condensateiof the vapors thus expelled are of the most volatile character and hence of the greatest commercial value as a liquid fuel.

One of the objects of this invention is to provide a method of recovery of the vapor condensates from storage tanks and to organize apparatus for such purpose which is economic of construction, installation and maintenance.

Another object of the invention is to provide apparatus to relieve the hazards of the vapor pressure formed within a bulk storage tank and to construct the apparatus so that the condensates may be readily accumulated and conveniently dispensed therefrom.

Other objects more or less ancillary of the foregoing and the manner in which all the various objects are realized will appear in the following description which, considered in connection with so the accompanying drawing, sets forth the preferred embodiment of the invention.

In the accompanying drawing which illustrates the preferred embodiment of the invention there is shown a storage tank 10 mounted .in the conventional manner upon a structural steel frame 11 set upon footing columns 12. The tank is provided with a filling line 13 and a dischargeconduit 14. The man hole 15 formed in the top of this tank is constructed, herein, with an air-tight seal. In the uppermost portion of the tank there 63 is'a conduit 16 formed with the usual pipe con nections to extend downwardly to a subterranean tank 17 which is preferably installed at least three 4 feet below the surface of the earth.

The portion of the conduit 16 which extends 65 within the tank is perforated throughout its length to provide for the ready egress of condensates at the fiuid level of the gasoline within the tank 1'7. In the uppermost portion of the tank there is a stand pipe 18 which extends above 10 ground and is open to atmosphere through an arcuated pipe T 19. The portion of the stand pipe 18 within the tank is provided with a per-,v forated T 20, the apertures 21 therein being relatively small in order to prevent a draught or a the mouth thereof.

When the gasoline withinthe storage tank 10 is agitated or when the tank becomes heated by the sun or through climatic changes, a light expansible vapor or gas rises from the gasoline within the tank and is forced, due to the pressure 90.?"

thereof, to flow through the conduit 16 and into the tank 1'1. As these gases reach the portion of the pipe below the earth's surface and the cooler atmosphere of the underground tank 17,

which is substantially 62 F., they will be con- 53' tracted, condensed to a liquid state and entrapped within the tank 17. The battled outlet or condenser on the stand pipe 18 within the subterranean tank inhibits the flow of gases therethrough so that when the pressure in pipe 16 1 0 rises above a certain point the safety valve 26 will pop-off. Further in case of loading of the conduit 16, caused by complete filling of tank 17 with liquid the pressure relief valve 26 in the upper portion of the conduit will function. to release the gas from the storage tank 10. It has been found, however, that such vapors as are not readily condensed whenthey reach the tank 1'7 are arrested by the escapement T 20 associated with the vent line 18. Illustrative of the opera- 11.0"-

tion of the condensing method heretofore described, assume the tank 10 being exposed to an atmospheric temperature of 90 F. and the tank half filled with gasoline. Under these conditions a large area of liquid will be exposed to tank atmosphere where the gasoline will surrender vapors which expand to a pressure suflicient to effeet the circulation thereof. Since relatively low pressure is suflicient to cause an active circulation of the gases they will readily flow through the line 18 and to the cool atmosphere (62 F.) of the subterranean tank 17. The thermal variation between the two reservoirs is adequate to cause condensation and thus eii'ect the recovery of the fuel which hitherto has been dissipated from the storage tank in gaseous form and lost.

When gasoline is withdrawn from storage tank 10, a vacuum would be created therein unless relieved by the intake of gases and air through sub terranean tank 17. If gases from the storage tank 10 are in suspense and in process of condensation within the subterranean tank 17 at the time of withdrawing liquids from storage tank 10, then atmospheric air will -be admitted into stand pipe 18, passing through subterranean tank 17, through conduit 16 into storage tank 10. likewise at night time, when the gases in storage tank 10 contract, creating a lower pressure therein, a circulation of cool atmospheric air will pass through the subterranean tank 17 and into the storage tank 10.

Although the foregoing description is necessarily of a detailed character, in order that the invention may be completely set forth, it is to be understood that the specific terminology is not intended to be restrictive or confining, and that various rearrangements of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. In combination with a storage tank, a vapor recovery unit comprising an underground tank, a conduit connected thereto and with said storage tank at the top thereof, said conduit extending into the underground tank and said extended portion, being provided with perforations, a vent for said underground tank and so positioned as to permit the flow of gases from and into said storage tank to pass through said underground tank, the flow of said gases within said underground tank being retarded by perforations in said conduit.

2. In combination with a storage tank, a vapor recovery unit comprising a subterranean tank, a pipe connected thereto and with said storage tank at the top of the liquid level thereof, a vent for said subterranean tank so positioned as to permit the flow of gases from or into said storage tank to circulate through said subterranean tank, said pipe and vent extending within said subterranean tank, and provided with perforations in said extended portions to retard the flow of gases through said subterranean tank.

3. In combination with a storage tank, a vapor recovery unit comprising a subterranean tank, a fluid connection intermediate said subterranean tank and the top of said storage tank, and an atmospheric vent provided with a continuously open condensing means for said subterranean tank so positioned as to permit the flow of gases from or into said storage tank to pass through said subterranean tank.

4. In combination with a storage tank, a vapor I condensate recovery unit, comprising a subterranean tank, a pipe connected thereto and above the liquid level of said storage tank, a vent for said subterranean tank provided with a condensing means which permits circulation of the gases from the subterranean tank through the vent.

5. In combination with a storage tank, a vapor recovery unit comprising a subterranean tank, a fluid connection interposed between said subterranean tank and the top of said storage tank, an atmospheric vent for said subterranean tank, and a condensing means associated with said vent, said condensing means permitting circulation of gases from the tank through the vent.

KENNETH S. CLAPP. 

